Electromagnetic pump



DeC- 5 1950 J. W. DlcKEY ETAL 2533i@ ELECTROMAGNETIC PUMP Filed May l2, 1947 2 Sheets-Sheec l 2 Sheets-Sheet 2 J. W. DICKEY ETAL ELECTROMAGNETIC PUMP Dec. 5, 1950 Filed May 12, 1947 enema Dec. s, 195o ELECTROMAGNETIC PUMP John W. Dickey, Newiield, and Norwood S. Trout,

Jr., Elmira, N. Y

., assignors to Bendix Aviation Corporation, Elmira Heights, N. Y., a corporation of Delaware Application May 12, 1947, Serial No. 747,528

2 Claims. (Cl. 172-126) The present invention relates to an electromagnetlcally operated pump and more particularly to a pump for supplying fuel to the carburetor of an internal combustion engine.

When pumps of the constant stroke spring actuated type are used to supply fuel to internal combustion engines, it has been found that if the pump is designed to furnish an adequate supply of fuel for the maximum demand, the spring pressure at the start of the discharge stroke may be such that during idling of the engine some excess fuel may be forced past the float valve of the carburetor causing the carburetor to flood. On the other hand, if the spring pressure is reduced to a point where flooding will never occur, the pump must be enlarged and consequently made more expensive in order to insure an ample delivery of fuel for maximum consumption.

It is an object ofthe present invention to provide a novel electromagnetically voperated pump which is efficient and reliable in operation while being simple and economical in construction.

It is another object to provide such a device in which the delivery pressure is limited to a predetermined maximum.

It is another object to provide such a device in which the pressure of the fuel delivered is maintained substantially constant over a wide range of output volume.

It is another object to provide such a device including improved actuating and controlling means for the pump.

Further objects andadvantages will be apparent from the following description taken in connection with the accompanying drawing, in which: A.

Fig. 1 is a vertical -substantially mid-sectional view of a preferred embodiment of the invention, the section through the contact chamber being taken substantially on the line I-I of Fig. 2;

Fig. 2 is a section'taken substantially on the line 2--2 of Fig. 1;

Fig. 3 is a detail of the lower partition with the by-pass valve spring partly broken away; and

Fig. 4 is a graph of pressure plotted against output volume in a typical pump, both with and without the pressure limiting feature. f

In Fig. l of the drawing, there is illustrated a cylindrical casing I of magnetic material having a removable closure cap 2 on its lower end, and a combination cap and y air dome 3 fixed on its upper end. A partition 4 of magnetic material is rigidly mounted in the casing I so as to form an inlet chamber 5 in the lower part of the casing.

A second partition i also of magnetic material is mounted in the casing I in spaced relation to 2 the partition 4, and a solenoid 1 is mounted between the partitions 4 and 6 so that said partitions form pole pieces for the solenoid.

A cylinder 8 of non-magnetic material is fixed at its lower end in the partition 4 and passes up through the solenoid 'I and partition 6, terminata ing at a third partition member 9 to which the upper end of the cylinder is rigidly xed as indicated at II, whereby the partition 3 defines an outlet chamber I2 in the casing I.

A hollow piston I3 of magnetic material is slidably mounted in the cylinder 8, and a spring I4 seated in a cup I5 fixed to the partition 4 is arranged to urge the piston I3 toward the upper f or discharge end of the cylinder 8.

Means for preventing backward fiow of liquid through the piston I3 is provided in the form of a check valve I8, and a second check valve I 1 is preferably provided in the bottom of the vcup I5 to allow entry of liquid therein but to prevent backward flow thereof.

Means are provided for energizing the solenoid 1 to draw the piston I3 against the action of spring I4 and thereby cock the spring for its discharge stroke. As here shown, this means comprises a battery I8 grounded at I9 and connected by a switch 2| and lead 22 to a sealed connector 23. One end of the solenoid winding is connected by a lead 24 to the terminal connection 23 while the opposite end is connected by a lead 25 to a fixed contact 26 mounted on a spring strip 30 supported by a flexible U-shaped bracket 21. The bracket 21 is mounted on the partition 6,- insulated therefrom as indicated at 28 and 29. The bottom of the bracket is bowed upward as shown at 3I and a screw 32 traversing said portion is threaded into the partition 6, whereby adjustment of the screw will cause flexure of the arms of the bracket 21 so as to adjust the position of the contact 26.

An armature 33 (Fig. 2) of magnetic material shaped to conform to the exteriorof the cylinder 8 is pivotally mounted adjacent the upper end of the cylinder as by means of a fiexible leaf 34 anchored to the partition 8 as shown at 35. The

leaf 34 is elastic and performs the function of a spring, tending to move the armature away from the cylinder, such motion being limited by suitable means such as an abutment 38. A mo .fable Contact 31 is .carried by the armature 33 in position to engage with the fixed contact 26 when the armature moves toward the cylinder 8. Since said armature is grounded through the leaf 34, engagement of the contacts completes the circuit f'or energizing the solenoid 1. Means for actuatlng the armature to close the contacts is pro vided in the form of a ring-shaped permanent magnet 38 fixed on the upper end of the piston I3 as by soldering or brazing. The magnet 38 is magnetized axially with the same polarity as the solenoid 1. In other words, if, when the solenoid 1 is energized, the upper end of the solenoid and consequently the upper end of the piston I3 becomes a north pole, the magnet 38 is arranged to y have its north pole at the upper end thereof. The energization of the solenoid thus reenforces the magnet and increases the length of the stroke of piston I3. A soft iron pole piece 39 is preferably iixed on the upper end of the magnet 38 in order to localize and increase the attraction of the magnet for the armature 33.

In order to limit the maximum pressure of the liquid in the outlet chamber I2 caused by the action of thev pump, a by-pass conduit 4I is arranged to traverse aligned openings 42, 43 and 44 in the partitions 9, 6 and 4, respectively, the openings being sealed by solder or other suitable means. The partition 4 has its opening 44 enlarged as shown at 45, to receive a ball valve 46 which is yieldably held on its seat 41 by a flat spring 48 fixed to the underside of the partition 4 as shown at 49. The spring 48 is designed to exert suflicient pressure on the ball 46 to maintain the by-pass 4I closed until the unit pressure in the outlet chamber I2 exceeds a predetermined value, when this pressure is exceeded the valve u 46 opens and prevents a further rise in pressure.

In operation, upon closure of the switch 2I the piston I3 being at the upper end of its stroke and the contacts 26, 31 being closed by the attraction of the magnet 38, the soenoid 1 is energized to 2 draw the piston I3 down thus compressing the spring I4 until the pole piece 39 moves away from the armature 33, thus allowing the contacts 31, 26 to open. The spring I4 is then effective to raise the piston I3, thereby pumping the liquid trapped in the cylinder above the piston I3 into the discharge chamber I2. As soon as the piston rises to a point where the magnet 38 becomes efi'ective to attract the armature 33, the contacts 31, 26 reclose and the action is repeated.

If the engine being supplied with fuel is idling so that there is only a small demand for fuel, the 'pump works slowly and the peak pressure generated at the initiation of the pumping strokes may be suilicient to unseat the by-pass vave 46. The pressure inthe outlet chamber I2 is thereby limited and maintained substantially constant. In Fig. 4, the relation between output pressure and volume delivered by a typical pump equipped with a by-pass as herein described isl shown by the solid line graph; while the broken line graph shows the operation of the same pump when the by-pass is sealed oil?. It will be noted that when the by-pass is functioning, the maximum output pressure is limited to 4.5 lbs. per square inch, whereas when the by-pass is plugged, the pressure at minimum volume goes up to 7.7 lbs. per square inch. Such a peak pressure may be enough to unseat the iioat valve oI.' a carburetor and cause flooding. This condition is effectively prevented, however, by the opening of the springloaded valve of .the by-pass, as clearly shown by= the solidline graph.

Although but one embodiment of the invention has been shown and described in detail, it will be understood that other embodiments are possible and that changes may be made in the proportions and arrangement of the parts without departing from the spirit of the invention as defined i!! the claims appended hereto.

actuated stroke including a permanent magnetv fixed at one end on one end of the piston, an

' armature shaped to conform to the external surface of the cylinder pivotally mounted to swing in a horizontal plane toward and from the cylinder, and so located that the permanent magnet comes into substantial registry therewith at the end of the spring-actuated stroke of the piston, a spring urging the armature away from the cylinder, and contacts closed by movement of the armature toward the cylinder, in which said contacts include a movable contact mounted on said armature and -a fixed contact adapted to cooperate therewith; a

flexible U-shaped bracket carrying the fixed contact and means for mounting the bracket including a screw traversing the bottom (thereof, the bottom of said bracket being normally bent convexly, so that adjustment of the mounting screw fiexes the bracket.

2. In an electromagnetic reciprocating motor, a cylindrical casing, a non-magnetic cylinder, partitions in the casing supporting the cylinder co-axially therein, a piston of magnetic material slidably mounted in the cylinder, a spring urging the piston toward one end of the cylinder, a solenoid between said partitions adapted when energized to retract the piston and cock the spring, and means for energizing the solenoid when the piston reaches the end of its springactuated stroke including a permanent magnet fixed at one end on one end of the piston, an armature shaped to conform to the external surface of the cylinder pivotally mounted to swing in a horizontal plane toward and from the cylinder,

and so located that the permanent magnet comes into substantial registry therewith at the end of the spring-actuated stroke of the piston, a spring urging the armature away from the cylinder, and contacts closed by movement of the armature toward the cylinder, including further a pole piece of magnetic material such as iron fixed to the free end of the magnet and having substantially the same diameter as the piston, to localize and increase the attraction of the magnet for the armature.

JOHN W. DICKEY. NORWOOD S. TROUT, JR.

REFERENCES CITED The following references are of record in the le of this patentz' k UNITED STATES PATENTS Number Name Date 1,845,998 Gregory Feb. 16, 1932 1,908,092 Whitted May 9, 1933 2,373,138 Morith Apr. 10, 1945 2,430,151 Whitted Nov. 4,' 1947 2,458,770 Dickey et al. Jan. 11, 1949 FOREIGN PATENTS Number Country Date 350,667 Great Britain June 18, 1931 

